### Date : 2024-11-02 10:55 ### Topic : Mitral regurgitation #cardiology ---- **Mitral Regurgitation (MR)** is a condition where the mitral valve in the heart fails to close properly, allowing blood to flow backward from the left ventricle (LV) into the left atrium (LA) during systole. This regurgitation leads to increased volume and pressure in the LA and, eventually, in the LV, which can cause various symptoms and complications. ### 1. **Pathophysiology and Mechanism** - **Regurgitation of Blood**: In MR, when the LV contracts (systole), blood flows back through the mitral valve into the LA instead of solely being pumped into the aorta. This backflow results from inadequate closure of the mitral valve. - **Volume Overload**: The LA receives both blood from the lungs and regurgitated blood from the LV, causing **volume overload** in both the LA and the LV. - **Compensatory Changes**: To accommodate the increased volume, the LA dilates, and over time, the LV also dilates (eccentric hypertrophy) to maintain forward stroke volume and cardiac output. ### 2. **Causes of Mitral Regurgitation** MR can be classified as **primary (structural)** or **secondary (functional)** based on the underlying cause: - **Primary MR (Structural Abnormalities)**: Issues directly related to the mitral valve structure. - **Mitral Valve Prolapse (MVP)**: Most common cause in developed countries; the mitral leaflets bulge backward into the LA, often with associated leaflet or chordae abnormalities. - **Rheumatic Heart Disease**: Causes thickening and deformity of the mitral valve leaflets and is a common cause in developing countries. - **Infective Endocarditis**: Infection can damage the valve leaflets, causing MR. - **Degenerative Calcification**: Calcification of the mitral annulus, particularly in older adults, can cause MR by restricting leaflet movement. - **Secondary MR (Functional Abnormalities)**: MR occurs as a result of changes in LV structure or function. - **Left Ventricular Dilation**: Conditions like dilated cardiomyopathy lead to stretching of the mitral annulus, causing MR. - **Ischemic Heart Disease**: Myocardial infarction, especially of the papillary muscles, can impair proper closure of the mitral valve. ### 3. **Symptoms of Mitral Regurgitation** Symptoms vary depending on the severity of MR and whether it is acute or chronic: - **Chronic MR**: - **Dyspnea (Shortness of Breath)**: Especially during exertion or when lying flat (orthopnea), due to pulmonary congestion. - **Fatigue and Weakness**: Reduced cardiac output and inefficient blood flow can lead to tiredness. - **Palpitations**: Caused by increased left atrial size and possible atrial fibrillation. - **Peripheral Edema**: In severe, long-standing MR, right-sided heart failure symptoms, such as swelling in the legs and abdomen, can develop. - **Acute MR** (such as from papillary muscle rupture in a heart attack): - **Sudden Severe Dyspnea**: Due to rapid onset of pulmonary edema. - **Hypotension and Cardiogenic Shock**: In severe cases, cardiac output drops suddenly, causing shock. ### 4. **Physical Examination Findings** Physical examination can reveal specific findings that help diagnose MR: - **Holosystolic (Pansystolic) Murmur**: A blowing murmur heard best at the **apex** of the heart, radiating to the **axilla**. - **Wide Split of S2**: Due to early closure of the aortic valve (A2) and delayed closure of the pulmonic valve (P2). - **S3 Gallop**: Indicates increased volume in the left ventricle due to the regurgitant blood flow. - **Displaced Apical Impulse**: The left ventricular impulse may be displaced laterally due to LV dilation. ### 5. **Diagnosis of Mitral Regurgitation** Diagnosis is primarily made using imaging, with echocardiography being the gold standard: - **Echocardiography**: - **Transthoracic Echocardiogram (TTE)**: Shows the extent of regurgitation, LV function, and LA size. Color Doppler imaging can visualize the regurgitant jet into the LA. - **Transesophageal Echocardiogram (TEE)**: Provides more detailed imaging of the mitral valve, especially in surgical planning or in cases of infective endocarditis. - **Assessment of Severity**: The severity of MR is graded based on the regurgitant jet area, effective regurgitant orifice area (EROA), and regurgitant volume. - **Electrocardiogram (ECG)**: May show signs of left atrial enlargement, LV hypertrophy, or atrial fibrillation. - **Chest X-ray**: Can show left atrial enlargement and pulmonary congestion in chronic MR. ### 6. **Management and Treatment of Mitral Regurgitation** Treatment depends on the severity of MR and the presence of symptoms. - **Medical Management**: - **Diuretics**: Help reduce symptoms of fluid overload and pulmonary congestion. - **ACE Inhibitors or ARBs**: Used to reduce afterload and improve forward cardiac output, especially in patients with heart failure. - **Beta Blockers**: Particularly in patients with atrial fibrillation or heart failure. - **Anticoagulation**: If atrial fibrillation is present, anticoagulation is recommended to prevent thromboembolic events. - **Surgical Management**: - **Mitral Valve Repair**: Preferred over replacement when feasible, as it preserves the patient’s own valve and offers better long-term outcomes. - **Mitral Valve Replacement**: Required if the valve is severely damaged and cannot be repaired. - **Indications for Surgery**: Indicated for symptomatic severe MR or asymptomatic patients with signs of LV dysfunction (e.g., reduced ejection fraction, LV dilation). - **Transcatheter Mitral Valve Repair (MitraClip)**: - A minimally invasive option for patients with symptomatic severe MR who are high-risk candidates for open-heart surgery. The MitraClip device reduces regurgitation by approximating the mitral leaflets, creating a double orifice. ### 7. **Prognosis and Complications** - **Prognosis** depends on the severity of MR and the timeliness of treatment. - **Complications**: - **Atrial Fibrillation**: Due to left atrial dilation, MR often leads to atrial fibrillation, which increases the risk of stroke. - **Heart Failure**: Chronic MR can progress to left-sided heart failure, and in severe cases, it can cause right-sided heart failure. - **Pulmonary Hypertension**: Increased pressure in the LA can lead to increased pressure in the pulmonary circulation, resulting in pulmonary hypertension. - **Endocarditis**: The abnormal mitral valve in MR is susceptible to infection, which can worsen regurgitation and require urgent surgical intervention. ### Summary - **Mitral Regurgitation** occurs when the mitral valve fails to close properly, allowing blood to flow back into the left atrium during systole. - **Causes**: Include mitral valve prolapse, rheumatic heart disease, ischemic heart disease, and left ventricular dilation. - **Symptoms**: Chronic MR causes dyspnea, fatigue, and palpitations, while acute MR can cause severe dyspnea and shock. - **Diagnosis**: Made through echocardiography, ECG, and sometimes TEE. - **Treatment**: Medical management for symptom control, surgical repair or replacement for severe cases, and MitraClip for high-risk patients. If you’d like to delve deeper into the management strategies or surgical options, feel free to ask! ### Reference: - ### Connected Documents: -